Is 32b the normal bra size for an 12 year old?

I'm 12 years old, 5ft 2, weigh 90 lbs and i wear 32b . Compared to the other girls in my class i totally look and feel totally flat. Is this normal. i feel self conscious and almost like an empty shell. when we change for p.e. i try go in the bathroom stalls and change or put my pe shirt on and take off the other one underneath. i was just wondering is 32b the right size cuz there are girls my age with boobs in a different cup size.